Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Dec Sun 17, 2017 1:32 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 33 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Tue 05, 2017 2:54 pm 
Member

Joined: Jul Mon 25, 2016 11:34 am
Posts: 268
Location: Wilton IA
I have tried cleaning the switch and I replace the 6SA7 tube, but to no avail. I have been trying to check resistors, but the schematics are confusing.

On the schematic with only the BC band, it shows resistor 7 coming off of pin 5, but in the full schematic it shows resistor 9. I don't know which resistor it really is.

Also in the radio there are two resistors coming off pin 5 as seen in the picture I previously posted. One being Green-Black-Black and the other Red-Green-Orange. I don't think either of these match the other resistors well, but maybe I am missing something that someone here could point out.

Thanks so much for all of the help,
Noah


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Thu 07, 2017 3:17 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1491
Location: Silver Spring MD, USA
wowsk wrote:
I have tried cleaning the switch and I replace the 6SA7 tube, but to no avail. I have been trying to check resistors, but the schematics are confusing.

On the schematic with only the BC band, it shows resistor 7 coming off of pin 5, but in the full schematic it shows resistor 9. I don't know which resistor it really is.

Also in the radio there are two resistors coming off pin 5 as seen in the picture I previously posted. One being Green-Black-Black and the other Red-Green-Orange. I don't think either of these match the other resistors well, but maybe I am missing something that someone here could point out.

Thanks so much for all of the help,
Noah


Hi Noah -

I'm not 100% sure why there are 2 resistors there. Looking at your picture, it's a bit hard to tell where they connect

And yes, somebody numbered something wrong on the schematics. It *seems* that the R9 number on the factory schematic is correct. That value is 25K (schematic says "25M" but that's the old system wherein "M" is for a thousand). And that value would be correct for the red bodied resistor in your picture.

Couple of things: to check that it is indeed R9, you can check to see that one end goes to ground. Assuming it does, and therefore is that resistor, disconnect one end and test its value. If it's way off, it could be the culprit.

You can also trace the value of the second resistor with the green body and see where it connects. I make it out to be 50 ohms (green-black-black), but I don't see that value on the schematic. You can check its value as well, but I'm not sure it's critical to what we're trying to troubleshoot.

The other thing to check is the two mica caps, C18 and C19. Historically these are thought to be reliable over time, but now folks are reporting them going bad. It's probably worth replacing them - the modern replacement for C18 (.0002uF) would be 200pf, and C19 would be 50pf.

-Kevin

_________________
Crawls Backward When Alarmed: Guitars, amps, vintage radios and more.


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sat 09, 2017 12:57 pm 
Member

Joined: Jul Mon 25, 2016 11:34 am
Posts: 268
Location: Wilton IA
I replaced R9 it measured 31.6K ohms and that was about 25% off. I removed the 50 ohm resistor too. Now I can get signal by touching pin 4 of the RF amp with the multimeter lead. I don't have any pF caps so while I am waiting I am going to check the resistors on the automatic volume control, and clean the switches once again.

If any has anymore suggestions let me know.

Thanks for all of the help,
Noah


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sat 09, 2017 1:26 pm 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 9104
Location: Victoria, Australia
If you had the schematic, a lot of this drama was likely avoidable, as you knew the resistor values from it. These should have been checked as you changed the caps. I have always found this a wonderful way of avoiding the frustration & rework, when the set fails to power up & make radio noises. Rework can cause damage.

I think a good idea is to check all resistors. Not all will read accurately, but any that read substantially high "in circuit" are commonly duds and should be checked out of circuit (one end only needs to be out of circuit).

Marc


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sat 09, 2017 10:36 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1491
Location: Silver Spring MD, USA
wowsk wrote:
I replaced R9 it measured 31.6K ohms and that was about 25% off. I removed the 50 ohm resistor too. Now I can get signal by touching pin 4 of the RF amp with the multimeter lead. I don't have any pF caps so while I am waiting I am going to check the resistors on the automatic volume control, and clean the switches once again.

If any has anymore suggestions let me know.

Thanks for all of the help,
Noah


Good that you can get signal touching the RF amp.

I take it you've ordered some new low value caps?

-Kevin

_________________
Crawls Backward When Alarmed: Guitars, amps, vintage radios and more.


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sat 09, 2017 11:07 pm 
Member

Joined: Jul Mon 25, 2016 11:34 am
Posts: 268
Location: Wilton IA
I haven't ordered any low value caps, my grandpa had a few.

I checked the AVC and the second resistor, R8, was 1.7 meg. I am going to replace that first, and see if it helps, because that it quite away off.

I think I will check all resistors from now on because this radio is showing just how many can be out of tolerance.

Thanks for all of the help,
Noah


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sun 10, 2017 11:18 am 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 9104
Location: Victoria, Australia
And what vintage caps were Grandpa's? If they are NOS Wax Paper, they will likely be duds.

Marc


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sun 10, 2017 2:56 pm 
Member

Joined: Jul Mon 25, 2016 11:34 am
Posts: 268
Location: Wilton IA
No, they were pretty new, and I tested them first. They look like this:
http://www.justradios.com/mica.html


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Sun 10, 2017 10:29 pm 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 9104
Location: Victoria, Australia
If it is them they are Mica & here, rarely fail. Otherwise they may be red or green caps & have a voltage on them of either 100V or 630V.

Marc


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Tue 12, 2017 12:12 am 
Member

Joined: Jul Mon 25, 2016 11:34 am
Posts: 268
Location: Wilton IA
It's WORKING!!! :)

I kept working back until I came to the antenna coil. I looked around for a bit until I finally saw that the thin wire leading to the terminal strip had been broken. I soldered that on and now it work great!

Thanks so much for all of the help everyone. I learned so much information!

Noah


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Tue 12, 2017 3:14 am 
Moderator
User avatar

Joined: Feb Sun 01, 2009 2:56 pm
Posts: 9104
Location: Victoria, Australia
That's a relief: Very common problem, so don't feel left out. This is why I encourage testing resistors as you change the caps. Any work risks damage: Rework increases the likelihood of damage.

I have always said "You learn a lot from a set that fails to run".

Marc


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Wed 13, 2017 10:07 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1491
Location: Silver Spring MD, USA
Excellent.

And you did some troubleshooting in the process you can use in the future.

That set should be a good performer, with an RF amp and p-p outputs.

-Kevin

_________________
Crawls Backward When Alarmed: Guitars, amps, vintage radios and more.


Top
 Profile  
 
 Post subject: Re: Airline 04BR-907A Problems
PostPosted: Dec Wed 13, 2017 11:03 pm 
Member
User avatar

Joined: Nov Mon 06, 2017 7:45 pm
Posts: 72
Location: Sherwood, Oregon
wowsk wrote:
It's WORKING!!! :)

I kept working back until I came to the antenna coil. I looked around for a bit until I finally saw that the thin wire leading to the terminal strip had been broken. I soldered that on and now it work great!

Thanks so much for all of the help everyone. I learned so much information!Noah


All right! You spanked the Monkey! Get it? . . .Monkey Wards . . . Airline . . . Never mind.
May you can add "solved" to this topic.


Top
 Profile  
 
Post New Topic Post Reply  [ 33 posts ]  Moderators: Marcc, Norm Leal Go to page Previous  1, 2

All times are UTC [ DST ]


Who is online

Users browsing this forum: Brett_Buck, busterdog57, craterranch, simplex1040 and 23 guests



Search for:
Jump to:  


















Privacy Policy :: Powered by phpBB